1. Field of the Invention
The present invention generally relates to electro-optical readers, such as laser scanners for reading indicia, such as bar code symbols and, more particularly, to an integrated assembly of a trigger and a lightpipe for installation in such readers.
2. Description of the Related Art
Various electro-optical systems or readers have been developed for reading indicia such as bar code symbols appearing on a label or on a surface of an article. The bar code symbol itself is a coded pattern of graphic indicia comprised of a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers function by electro-optically transforming the pattern of the graphic indicia into a time-varying electrical signal, which is digitized and decoded into data relating to the symbol being read.
Typically, a laser beam from a laser is directed along a light path toward a target that includes the bar code symbol on a target surface. A moving-beam scanner operates by repetitively sweeping the laser beam in a scan line or a series of scan lines across the symbol by means of motion of a scanning component, such as the laser itself or a scan mirror disposed in the path of the laser beam. Optics focus the laser beam into a beam spot on the target surface, and the motion of the scanning component sweeps the beam spot across the symbol to trace a scan line across the symbol. Motion of the scanning component is typically effected by an electrical drive motor.
The readers also include a sensor or photodetector which detects light along the scan line that is reflected or scattered from the symbol. The photodetector or sensor is positioned such that it has a field of view which ensures the capture of the reflected or scattered light, and converts the latter into an electrical analog signal.
In retroreflective light collection, a single optical component, e.g., a reciprocally oscillatory mirror, such as described in U.S. Pat. No. 4,816,661 or U.S. Pat. No. 4,409,470, both herein incorporated by reference, sweeps the beam across the target surface and directs the collected light to the sensor. In non-retroreflective light collection, the reflected laser light is not collected by the same optical component used for scanning. Instead, the sensor is independent of the scanning beam and has a large field of view. The reflected laser light may trace across the sensor.
Electronic control circuitry and software decode the electrical analog signal from the sensor into a digital representation of the data represented by the symbol that has been scanned. For example, the analog electrical signal generated by the photodetector may be converted by a digitizer into a pulse width modulated digitized signal, with the widths corresponding to the physical widths of the bars and spaces. Alternatively, the analog electrical signal may be processed directly by a software decoder. See, for example, U.S. Pat. No. 5,504,318.
The decoding process usually works by applying the digitized signal to a microprocessor running a software algorithm, which attempts to decode the signal. If a symbol is decoded successfully and completely, the decoding terminates, and an indicator of a successful read (such as a green light and/or audible beep) is provided to a user. Otherwise, the microprocessor receives the next scan, and performs another decoding into a binary representation of the data encoded in the symbol, and to the alphanumeric characters so represented. Once a successful read is obtained, the binary data is communicated to a host computer for further processing, for example, information retrieval from a look-up table.
Reading of the indicia is initiated by manual depression of a trigger, such as the trigger 210 depicted in FIG. 1 herein. FIG. 1 depicts a prior art reader, especially the reader 10 illustrated in U.S. Pat. No. 6,321,990, the entire contents of which are incorporated herein by reference thereto. The trigger 210 is mounted on the reader 10 and is depressable by the operator to actuate a trigger switch 224 mounted on a printed circuit board 180 in the handle 12. When the trigger switch 224 is depressed, an electrical trigger signal is generated by the switch closure and is used to initiate reading of a symbol.
FIG. 1 also shows a pair of differently colored light emitting diodes 236, 238 mounted on a printed circuit board 104 within the reader. These diodes 236, 238 serve as status indicators of reader operation. When illuminated, the light from each diode is conducted through a lightpipe 240 to and through an exterior wall 18 of the reader to visually advise the operator of a certain system function. The lightpipe 240 enhances and optimizes the status lights. For example, a green light from diode 238 can indicate that a symbol has been successfully read. A red light from diode 240 can indicate that the reading has failed. The combination of red and green lights can indicate faults in the reader. The two diodes can even be incorporated in a single diode package.
The trigger 210 and the lightpipe 240 are typically made of different materials and consist of two different parts. The trigger is typically installed in the reader by snap action, bonding or staking. The lightpipe is typically installed in the reader by bonding, heat staking, or ultrasonic welding. Some readers may overmold the lightpipe directly onto a housing of the reader, for example, on the exterior wall 18 of FIG. 1. However, the process of overmolding with the housing requires costly tooling and is difficult to achieve since the interface or parting line between the lightpipe and the housing is clearly visible to a customer. Blemishes at the interface between the lightpipe and the housing are unaesthetic and cannot be tolerated. The separate assembly of the trigger and the lightpipe is labor intensive. The making and assembling of these separate parts are costly.